Vintage Synth Repair

I would remove the jack board and inspect the jacks, as cold solder joints are very common on M1s.  Check that MIDI local is on.  Check the +/- 12 volts that runs the audio circuits.  


Also cold solder joints on the power supply are also common, check around the 12v regulators and bridge rectifier.

Every M1 or O1w that I work on gets the jack and power supply board inspected for cracks around devices and cold joints.  Why, because they all have them.  All.  


>________________________________
> From: pushwithlegs <pushwithlegs@...>
>To: vintagesynthrepair@yahoogroups.com 
>Sent: Monday, June 10, 2013 5:11 PM
>Subject: Re: [vintagesynthrepair] korg m1 still display "internal battery" error after replacing battery
> 
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>yes all the names of the programs/combos are visible however no audio is audible oddly enough.
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>On Mon, Jun 10, 2013 at 4:42 PM, Roger J <winking_n_nodding@...> wrote:
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>>  
>>After loading the programs or before for that matter, did any combo or programs appear in the LCD?
>>
>>
>>R
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>>>________________________________
>>> From: pushwithlegs <pushwithlegs@...>
>>>To: vintagesynthrepair@yahoogroups.com 
>>>Sent: Monday, June 10, 2013 4:29 PM
>>>Subject: Re: [vintagesynthrepair] korg m1 still display "internal battery" error after replacing battery
>>> 
>>>
>>>
>>>  
>>>Thanks for the response.
>>>I've had a few m1's over the years with the internal battery error - usually replacing it makes the error disappear and one simply reloads the presets via a RAM card to get it going.
>>>
>>>
>>>I measured the voltage as outlined and it is fine.
>>>
>>>The circuit board doesn't appear to have any damage or corrosion.
>>>
>>>
>>>Anyhow i just reloaded the sounds via RAM card to see if that would affect things vis a vis the internal battery message.
>>>
Interestingly the message remains however there is absolutely no audio output audible. (which i assumed before was related to the fact the battery needed to be replaced and there were no sounds)
>>>
>>>Also though i was able to load the presets via the RAM card my set of ORGAN cards won't show up (ie: i cannot press the card button to access those banks)
>>>any other ideas?
>>>cheers
>>>-Sam
>>>
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>>>On Thu, Jun 6, 2013 at 3:49 PM, Roger J <winking_n_nodding@...> wrote:
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>>>>  
>>>>Late to this thread.   Have you tried to reloaded the factory preload data?   Without putting the data back in, all you will have is one default sound.  You will need a USB to midi cable and windows media player too.  I can email you the file if you do not have it.    
>>>>
>>>>
>>>>
>>>>The next step would be to measure the voltage at the +battery terminal 
to ground and then pin 28 of U23 and U32; both with the power off.  
Both should be over 3 volts.  
>>>>The battery voltage is sent throught a 3 meg resistor, R29 to pin4 of IC29 which measures your battery voltage and it should also read 3 volts.
>>>>
>>>>
>>>>IC29 is also used for other functions, like pedals.  If you discharge static electricity into one of the pedal jack via mistakenly plugging in a 1/4 inch cable while you power cable is not plugged in and then walked over  to your mixer, touching the tip to a jack; then possible 35,000 volts will be discharged down through the shield connector that you are holding, down the cable into the M1 and discharging out thought the tip.  Result, one blown IC29.  If any of the other functions of U29 are bad too, replace IC29.  
>>>>
>>>>
>>>>
>>>>U29 does pitch bend, mod joy stick, mono pressure, pedals, and measure you battery.  It would have blown they multiplexer inside and there will be cross coupling of the items, like pedal could be partially shorted to mono pressure and battery or pitch bend to battery etc.
>>>>
>>>>
>>>>Moral, always put your grounded power cables in first and remove them last. A 1/4 tip is a dangerous thing!
>>>>
>>>>
>>>>>________________________________
>>>>> From: pushwithlegs <pushwithlegs@...>
>>>>>To: vintagesynthrepair@yahoogroups.com 
>>>>>Sent: Thursday, June 6, 2013 1:07 PM
>>>>>Subject: [vintagesynthrepair] korg m1 still display "internal battery" error after replacing battery
>>>>> 
>>>>>
>>>>>
>>>>>  
>>>>>hi all,
>>>>>I have the same problem a few others on here have encountered as regards replacing the internal battery and still receiving the "internal battery" error message.
>>>>>
>>>>>In my case there doesn't appear to be any leaky capacitors or damage to the circuit board from leakage.
>>>>>
>>>>>Any other ideas where to look/what to do if replacing the battery doesn't do the trick (i've tried a few different batteries - all brand new so it def isn't that!)
>>>>>cheers
>>>>>-Sam
>>>>>
>>>>>
>>>>>
>>>>>
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>>>
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